AVENE.E. 



373 



e. Panicle slender, uwn on the floral glume very 

 short and straight. 4 



e. Panicle very slender, awn of lowest floral glume 

 longer and bent when dry 6 



e. Panicle dense 7 



d. First glume 1-nerved (i) 



f. Panicle usually spikelike 7, 8, 9 



f. Panicle not spikelike (g) 



g. Spikelets 3-flowered 11, 13 



g. Spikelets 3-4-flowered. ... 12, 13, 14, 15 

 1. T. palustre (Michx.) Torr. Fl. U. S. 1 : 126 (1824). Avena 



Pennsylvanica L. Sp. PL 79 (1753) ? Avena Caroliniana Walt. 



Fl. Car. 81 (1788) ? Avena paktstris Michx. Fl. Bor. Am. 1 : 72 



(1803). T. Pennsylvanicum B. S. P. Prel. Cat. N. Y. 67 (1888). 

 A smooth and slender erect perennial, 50-90 cm. high. 



Leaf -blades flat, 8 cm. long, 5 mm. 



wide. Panicle narrow, loose, 10-20 



cm. long, rays capillary. Spikelets 2- 



flowered, compressed, lower floret awn- 

 less, the upper awued and raised on a 



slightly hairy rachilla nearly 3 mm. 



long and continued beyond as much 



farther; first empty glume lanceolate, 



1-uerved, 4-5 mm. long, second about 



one-fifth longer, elliptical-lanceolate, 



3-nerved; floral glume of the lower 



floret 5 mm. long, awnless, nearly 



smooth at the base, 3-nerved, closely 



resembling the second empty glume; 



floral glume of the upper floret shorter 



and narrower than the lower one, 



bearing a slender spreading or bent awn next the short bifid tip; 



palese about two-thirds as long as their glumes, bifid, nerves diverg- 

 ing. Anthers over 1 mm. long. 



For an account of a supposed hybrid between this species and 



Eatonia Pennsylvanica, see Bull. Torr. Club, 13:118 (1886). 



Fig. 66. — Trisetum palustre. 

 Spikelet. (Scribuer.) 



